Further development of a broad study concerned with the isolation and characterization of novel and hopefully clinically useful anticancer agents from various animal and plant organisms has been proposed. More specifically, the very necessary financial assistance requested would be used to complete the isolation and characterization of antineoplastic agents from confirmed active extracts of 42 marine invertebrates and vertebrates, 5 terrestrial arthropods, and 3 plants. Of the marine animals fractions, 40 species have T/C values of 150 or over in the National Cancer Institute's PS lymphocytic leukemia system and 2 are significantly cytotoxic in the National Cancer Institute's KB cell line. Among the analogously active terrestrial arthropods fractions from 3 PS active species and 2 KB active species have been selected. In the plant kingdom 2 PS and 2 KB active species are of special interest at present. All substances of potential use arising from the proposed investigation would be made available as rapidly as resources permit for study by the Division of Cancer Treatment of the National Cancer Institute.